Evaluation of a Microwave-Assisted Extraction Method for Lignan Quantification in Flaxseed Cultivars and Selected Oil Seeds

An optimized microwave-assisted extraction (MAE) method was evaluated through repeatability, recovery and efficiency testing. The repeatability tests, performed by three users over time, were not significantly different. The recovery of lignan throughout the extraction, preparation and analysis steps is 97.5% with a coefficient of variation <1%. The MAE method is efficient for extracting lignans from the plant matrix, and it achieves significantly higher extraction yields than the two established reference methods. The applicability of the MAE method was demonstrated by extracting lignans from a variety of plant samples. The secoisolariciresinol diglucoside (SDG) content of seven flaxseed cultivars grown in Saint-Mathieu-de-Beloeil, QC, in 2009 ranged from 14.6 to 18.9 mg SDG per gram of seed. Flax hulls produced in Winchester, ON, in 2010 were very rich in lignan; their SDG content was 40.0 mg/g of flax hull. Sesame seeds contained 0.18–1.89 mg SECO (aglycone of SDG) per gram of seed, with significant differences among black, white and brown sesame seed. Chia seeds contained 0.99–1.29 mg SECO per gram of seed, with significant differences among batches of seeds. Sunflower seeds had 0.046 mg SECO per gram of sample and almonds had 0.029 mg SDG per gram of sample. The optimized and evaluated MAE method is recommended for the general analytical quantification of lignans in plant samples.     

亚麻木酚素解聚增效及油相迁移特性研究进展

木酚素是亚麻籽中极具代表性的活性物质,具有抗氧化、抗炎、抗癌、抗血管疾病等多种生理功能。在亚麻籽内,游离态木酚素较少,多数与其他分子结合以多聚体形式存在;大多数木酚素存在于种皮中,在压榨制油时难以释放。多聚体的存在和亚麻壳的束缚作用,都限制了亚麻籽木酚素的有效利用。本文结合近几年的研究报道,重点从萌发、物理场处理、酶以及酸碱水解的角度,对亚麻木酚素大分子的解聚增效特性、油相迁移特性及相关应用研究进行阐述,以期为亚麻籽中木酚素的靶向调控、高值化利用提供理论依据。     

Flaxseed: a potential source of food, feed and fiber

Flaxseed is one of the most important oilseed crops for industrial as well as food, feed, and fiber purposes. Almost every part of the flaxseed plant is utilized commercially, either directly or after processing. The stem yields good quality fiber having high strength and durability. The seed provides oil rich in omega-3, digestible proteins, and lignans. In addition to being one of the richest sources of α-linolenic acid oil and lignans, flaxseed is an essential source of high quality protein and soluble fiber and has considerable potential as a source of phenolic compounds. Flaxseed is emerging as an important functional food ingredient because of its rich contents of α-linolenic acid (ALA), lignans, and fiber. Lignans appear to be anti-carcinogenic compounds. The omega-3s and lignan phytoestrogens of flaxseed are in focus for their benefits for a wide range of health conditions and may possess chemo-protective properties in animals and humans. This paper presents a review of literature on the nutritional composition of flaxseed, its health benefits, and disease-prevention qualities, utilization of flaxseed for food, feed, and fiber, and processing of flaxseed.     

The effective parameters for subcritical water extraction of SDG lignan from flaxseed (Linum usitatissimum L.) using accelerated solvent extractor

The aim of this study was to investigate the effective parameters for subcritical water extraction of secoisolariciresinol diglucoside (SDG) lignan from flaxseed using accelerated solvent extractor. For this aim, the influence of extraction parameters such as material shape (flaxseed, ground flaxseed meal and flaxseed meal sticks), temperature (120, 140, 160 and 180 °C), extraction time (15, 30, 60 and 90 min), pressure (1.500 and 2.000 psi), fresh water (5, 40 and 100 %) and sample amount (5 and 10 g) was studied. SDG lignan analysis has been carried out by LC–MS/MS. It was shown that material shape, temperature, extraction time and sample amount had significant effect on SDG lignan content in water extracts (p < 0.05). The highest amount (12.94 mg/g) and extraction yield (72.57 %) were obtained at 180 °C for 15 min, 1.500 psi and 40 % fresh water using 5 g of flaxseed meal sticks.     

亚麻木酚素对动脉粥样硬化的改善作用研究进展

木酚素是一种植物雌激素,存在于多种植物中,亚麻籽中含量最高。研究表明亚麻木酚素具有降低血脂、预防心血管疾病、抗氧化、抗癌、抗炎以及抗动脉粥样硬化(AS)等多种生理功能。虽然关于其抗AS的作用已有相关报道,但具体机制还有待进一步研究。AS是发生于动脉的多发性、慢性、炎症性疾病。目前关于其发病的确切机制尚不明确,但有研究表明高血脂、高血压、高血糖、氧化应激以及炎症反应等都是AS的危险因素。主要对亚麻木酚素对AS的改善作用进行综述,以期为亚麻木酚素功能性食品的研究开发提供借鉴。     

Subcritical water extraction of phenolic compounds from flaxseed meal sticks using accelerated solvent extractor (ASE)

Subcritical water extraction (SWE) is a technique based on the use of water as an extractant, at temperatures between 100 and 374 °C and at a pressure high enough to maintain the liquid state. SWE provides higher selectivities, low cost, and shorter extraction times. In this study, phenolic compounds in flaxseed (Linum usitatissimum L.) meal sticks were extracted with subcritical water using accelerated solvent extractor. For this aim, the interactions between temperature (160, 170, and 180 °C) and extraction time (5, 15, 30, and 60 min) for subcritical water extraction of SDG lignan, total phenolics, and total flavonoids from flaxseed meal sticks were investigated. The highest extraction yield of SDG lignan (77.01 %) in subcritical water extracts was determined at 160 °C for 60 min. However, high extraction yields were obtained as 70.67 and 72.57 % at 170 and 180 °C for 15 min, respectively. Also, the highest extraction yield of total phenolics (70.82 %) and total flavonoids (267.14 %) were determined at 180 °C for 15 min. Besides, high correlations between SDG lignan–total phenolics, SDG lignan–total flavonoids, and total phenolics–total flavonoids were obtained from 0.86 to 1 in water extracts.     

Validation of an Electrochemical Detection–High-Performance Liquid Chromatography Method for Simultaneous Determination of Lignans in Flaxseed (Linum usitatissimum L.)

Flaxseed is a major source of lignans, which are important bioactive compounds. The aims of this work were to validate a liquid chromatographic method for the rapid and simultaneous determination of the main lignans in flaxseed using high-performance liquid chromatography coupled with electrochemical detection and to analyze the composition of commercial samples of flaxseed. The performance criteria of the proposed method demonstrate that the method can be used for the analysis of secoisolariciresinol diglucoside (SDG), secoisolariciresinol (SECO), matairesinol (MATA), pinoresinol (PINO), lariciresinol (LARI), hydroxymatairesinol (HYDROXY), and isolariciresinol (ISOLARI) in flaxseeds at suitable levels. Calibration curves were determined for six different concentrations of standard solutions injected in triplicate. The sensitivity of the calibration curve was evaluated considering the confidence intervals of the intercept and slope. The limit of detection and limit of quantification were 7.4 and 10.9 μg/l, respectively, for LARI and 17.7 and 37.5 μg/l, respectively, for MATA. The relative standard deviation of repeatability values were lower than 2.59 %, which are acceptable because the Horwitz ratio values were 0.1 for all of the lignans. The recoveries of lignans were in the range of 74–100 % of SECO, which are consistent with the literature. The precision of the proposed method was determined by analyzing four flaxseed samples of different years and varieties. SDG was the main lignan present in all the samples, followed by ISOLARI and HYDROXY.     

亚麻籽有效成分的提取及其综合利用研究进展

亚麻是一年或多年生草本植物,在我国北方干旱半干旱地区大面积种植。亚麻籽是亚麻的种子,目前国内外对亚麻籽的开发主要侧重于对亚麻籽油的提取,而亚麻籽其他功能活性物质未得到有效开发利用。综述了亚麻籽油、亚麻籽胶、亚麻籽蛋白、亚麻籽木脂素4种天然有效成分的含量、组成、生理功能、提取技术以及在相关领域的应用等研究进展,旨在为亚麻籽有效成分的提取和综合开发利用提供技术参考。     

溶剂法提取亚麻籽木脂素(SDG)工艺优化研究

研究了溶剂法提取亚麻籽中木脂素的工艺,确定了单因素试验的最佳溶剂系统为70%的乙醇,提取温度为室温,时间为24 h。以木脂素得率为指标,采用二次正交旋转回归试验对溶剂法提取亚麻籽木脂素提取工艺进行优化,求得了二次正交旋转回归方程,确定了影响溶剂法木脂素得率的各因素的主次顺序依次为:提取时间、提取温度、乙醇浓度。用统计寻优方法进行方案寻优,可得乙醇浓度为70%、提取时间为28 h、提取温度为40℃时,木脂素得率最高为9.25%。     

开环异落叶松树脂酚的提取及其对乳液稳定性的影响研究

以含50%开环异落叶松树脂酚二葡萄糖苷(SDG)的亚麻木酚素粗提物(50%SDG)为水解原料,对制备开环异落叶松树脂酚(SECO)粗提物的HCl浓度和水解时间进行优化,进一步通过溶剂萃取、真空冷冻干燥工艺制备SECO粗提物,并将其应用于磷脂-亚麻籽油乳液体系中,研究水解前后亚麻木酚素粗提物对磷脂-亚麻籽油乳液在65℃高温储藏过程中稳定性的影响。结果表明:在HCl浓度1 mol/L、水解时间120 min的条件下水解,可制备SECO含量为65%的SECO粗提物(65%SECO);在磷脂-亚麻籽油乳液高温储藏(65℃)过程中,65%SECO组乳液粒径无显著变化,但对照组和50%SDG组乳液粒径增大;与对照组乳液相比,储藏7 d,65%SECO和50%SDG可分别将乳液中氢过氧化物含量降低11%和27%。由此可见,在磷脂-亚麻籽油乳液的高温储藏(65℃)过程中,50%SDG具有较好的抑制油脂氧化的效果,但通过水解制备的65%SECO能显著提高磷脂-亚麻籽油乳液的物理稳定性。     

Fatty acids and lignans in unground whole flaxseed and sesame seed are bioavailable but have minimal antioxidant and lipid‐lowering effects in postmenopausal women

Fatty acids and lignans in ground flaxseed and sesame seed are absorbed, metabolized, and exert some health benefits in vivo. However, it is unclear if they are absorbed, metabolized, and exert health benefits when consumed as unground whole seed; therefore, it was investigated in this study. In a randomized crossover study, 16 postmenopausal women supplemented their diets with food bars containing either 25 g unground flaxseed, sesame seed, or their combination (12.5 g each) (flaxseed+sesame seed bar, FSB) for 4 wk each, separated by 4 wk washout periods. Total serum n‐3 fatty acids increased with flaxseed (p<0.05) and FSB (p=0.064) while serum n‐6 fatty acids increased with sesame seed (p<0.05). Urinary lignans increased similarly with all treatments (p<0.05). Plasma lipids and several antioxidant markers were unaffected by all treatments, except serum γ‐tocopherol (GT), which increased with both sesame seed (p<0.0001) and FSB (p<0.01). In conclusion, fatty acids and lignans from unground seed in food bars are absorbed and metabolized; however, except for serum GT, the 25 g unground seed is inadequate to induce changes in plasma lipids and several biomarkers of oxidative stress.     

亚麻籽营养成分提取及其功能和应用研究进展

综述了亚麻籽中亚麻籽油、亚麻籽蛋白、亚麻籽多糖、亚麻籽胶、木脂素等主要营养成分的提取方法及其原理和优缺点,并对其调节脂质代谢、降低血糖血脂水平、改善心脑血管疾病、预防癌症等营养功能及在食品加工等领域的应用进行分析和讨论,以期为亚麻籽营养成分的提取和相关产品的进一步开发利用提供参考。     

Flaxseed proteins: food uses and health benefits

Flaxseed proteins are potent multi‐functional ingredients for food formulation owing to their techno‐functionalities, food preservation capacity, and health benefits. A possible synergistic effect with mucilage on their functionalities could be valuable even though this co‐product in flaxseed may limit the protein yield during their production processes. Their techno‐functional properties could also be considered in mixture with other flax bioactive components such as lignans and fibre to enhance the value of the flaxseed meal. The present paper reviews flaxseed protein uses in food and their health benefits. New perspectives according to consumers’ demand for products with health promoting bioactive components are also suggested.     

Dietary flaxseed lignan or oil combined with tamoxifen treatment affects MCF‐7 tumor growth through estrogen receptor‐ and growth factor‐signaling pathways

This study aimed to elucidate which component of flaxseed, i.e. secoisolariciresinol diglucoside (SDG) lignan or flaxseed oil (FO), makes tamoxifen (TAM) more effective in reducing growth of established estrogen receptor positive breast tumors (MCF‐7) at low circulating estrogen levels, and potential mechanisms of action. In a 2×2 factorial design, ovariectomized athymic mice with established tumors were treated for 8 wk with TAM together with basal diet (control), or basal diet supplemented with SDG (1 g/kg diet), FO (38.5 g/kg diet), or combined SDG and FO. SDG and FO were at levels in 10% flaxseed diet. Palpable tumors were monitored and after animal sacrifice, analyzed for cell proliferation, apoptosis, ER‐mediated (ER‐α, ER‐β, trefoil factor 1, cyclin D1, progesterone receptor, AIBI), growth factor‐mediated (epidermal growth factor receptor, human epidermal growth factor receptor‐2, insulin‐like growth factor receptor‐1, phosphorylated mitogen activated protein kinase, PAKT, BCL2) signaling pathways and angiogenesis (vascular endothelial growth factor). All treatments reduced the growth of TAM‐treated tumors by reducing cell proliferation, expression of genes, and proteins involved in the ER‐ and growth factor‐mediated signaling pathways with FO having the greatest effect in increasing apoptosis compared with TAM treatment alone. SDG and FO reduced the growth of TAM‐treated tumors but FO was more effective. The mechanisms involve both the ER‐ and growth factor‐signaling pathways.     

Cellulase-assisted release of secoisolariciresinol from extracts of flax (Linum usitatissimum) hulls and whole seeds

Extraction of secoisolariciresinol from seed hulls and whole seeds of flax was improved using an enzymatic step with cellulase R10 from Trichoderma reesei that allowed better yield as compared to β-glucosidase. The cellulase assisted extraction process was further optimised for different parameters such as duration and concentration of hydromethanolic extraction, duration of alkaline hydrolysis, pH, duration and incubation temperature as well as enzyme concentration. Best results were obtained using a method including the following successive steps: 16 h of 70% hydromethanolic extraction, 6 h of 0.1 M sodium hydroxide hydrolysis followed by a 6 h incubation with 1 unit ml⁻¹ of cellulase R10 in 0.1 M citrate–phosphate buffer pH 2.8 at 40 °C. Under these conditions, all forms of the main flax lignan were recovered as the aglycone form, i.e. secoisolariciresinol. Highest yields in secoisolariciresinol diglucoside (SDG) equivalent reached 7.72% of flaxseed hull (cv. Baladin) dry weight and 2.88% of whole seed (cv. Barbara) weight, thus allowing a significant improvement in comparison with published methods.     

A new mammalian lignan precursor,asarinin

Enterolactone (ENL) and enterodiol are mammalian lignans. Several plant lignans have been reported as precursors of mammalian lignans. However, asarinin (AS), a furofuran type lignan which occurs in medicinal plants and foods, has not been reported as mammalian lignan precursor to date. After the incubation of AS with human intestinal microflora, AS was converted to not only ENL, but also two more metabolites (mono-demethylenated and ring-cleaved compounds). Under the same conditions, sesamin (SM) was converted to ENL. Furthermore, chiral HPLC analysis showed that ENL produced from AS and SM was (−)-ENL. This is the first report which shows that AS is a mammalian lignan precursor.     

微生物发酵法提取亚麻木脂素

亚麻木脂素(SDG)是一种植物雌激素,具有多种生理功能。按2.5%的接种量将米曲霉Asp.oryzae 39#接种于亚麻籽粉,25～30℃发酵120h,再经丙酮提取,亚麻木脂素粗提物得率为21%～22%,SDG得率为16‰～17‰。发酵法提取SDG的提取率比未经发酵提高了50%。     

Role of dietary lignans in the reduction of breast cancer risk

Lignans are a large group of fiber-associated phenolic compounds widely distributed in edible plants. Some of the ingested plant lignans are converted by intestinal microbiota to enterolignans, enterodiol (END) and enterolactone (ENL), the latter of which has been thought to be the major biologically active lignan, and suggested to be associated with low risk of breast cancer. In line with this, administration of plant lignans which are further metabolized to ENL, or ENL as such, have been shown to inhibit or delay the growth of experimental mammary cancer. The mechanism of anticarcinogenic action of ENL is not yet fully understood, but there is intriguing evidence for ENL as a modulator of estrogen signaling. These findings have generated interest in the use of lignans as components of breast cancer risk reducing functional foods. Identification of target groups, who would benefit most, is of pivotal importance. Therefore, further identification and validation of relevant biomarkers, which can be used as indicators of lignan or ENL action and breast cancer risk reduction at different stages of the disease, are of importance.     

Stability of α-Linolenic Acid and Secoisolariciresinol Diglucoside in Flaxseed-Fortified Macaroni

Research was conducted to determine the stability of secoisolariciresinol diglucoside (SDG) and α‐linolenic acid (ALA) in flaxseed‐fortified macaroni. Macaroni was fortified with whole ground flaxseed (GWF) at levels of 10% to 20% and then dried under low temperature (LT, 40°C), high temperature (HT, 70°C), or ultrahigh temperature (UHT, 90°C). Macaroni was also fortified with 15% ground hull (GHF) or steam‐treated whole ground flaxseed (GSWF) and dried under UHT. The dried macaroni was stored for 32 wk under ambient conditions. Approximately 80% to 95% of the SDG was recovered, indicating that SDG was stable during the 32‐wk storage period. Total lipid and ALA levels in all flaxseed macaroni treatments remained unchanged throughout the 32‐wk storage. This observation was consistent across the drying conditions and flaxseed addition levels. Conjugated diene (CD) values indicated that macaroni fortified with GWF did not oxidize significantly during the 32‐wk storage for the macaroni dried under HT or UHT. However, a significant increase (P <0.05) in CD values for macaroni containing 10% and 20% flaxseed and dried using LT was observed at the 32‐wk storage period. Headspace volatile concentrations did increase over the storage period for macaroni containing GWF, but the increase was not significant. Significant increases (P < 0.05) in oxidation were found by 24 wk in GHF‐ and GSWF‐fortified macaroni. GWF macaroni dried at UHT, HT, or LT could be used as a way to improve our dietary consumption of ALA and SDG. However, use of steam as a method to inactivate unwanted enzyme activity is not recommended.     

脱毒亚麻饼粉对馒头品质的影响

研究了脱毒亚麻饼粉的不同添加比例对馒头比容、色泽、质构、感官和营养等品质的影响。结果表明:添加过多的脱毒亚麻饼粉,会使馒头的比容、扩展比下降以及色泽变暗;质构结果表明,随着脱毒亚麻饼粉添加比例的增加,馒头的硬度、胶粘性与咀嚼性不断增加,弹性、内聚性与回复性不断减小;馒头的油脂、蛋白质和灰分含量逐渐增加,氨基酸含量除脯氨酸外均呈增加趋势,木酚素含量也显著增加(p0.05),添加15%脱毒亚麻饼粉馒头的木酚素含量高达3.34 mg/g;馒头的感官评分随着脱毒亚麻饼粉的添加比例增大逐渐降低,但添加3%和6%脱毒亚麻饼粉馒头的感官评分显著高于其他添加脱毒亚麻饼粉的馒头,二者的感官评分均大于90且没有显著性差异,因添加6%脱毒亚麻饼粉馒头含有更多的油脂、蛋白质和木酚素等营养物质,故选择脱毒亚麻饼粉的最佳添加比例为6%。